Signals at highway crossings for high speed trains

ABSTRACT

The system differentiates between high speed trains and regular trains by having inductive means partly on the car and partly on the wayside for the high speed trains, while the regular speed trains cooperate with detector track circuit apparatus on the wayside for initiating the warning signals at the highway crossing. The inductive means on the wayside is located considerably in advance of the detector track circuit apparatus, but acts through such apparatus for initiating the warning signals. The warning signals given at the crossing continue their operation until the train has passed the highway. In one form of the invention, the car-carried equipment includes a radio transmitter which is initiated when the train passes the wayside inductive means. The transmission of such radio signal initiates the warning at the highway crossing and also causes the transmission of a return radio signal. If such return radio signal is promptly received, the train can continue in the usual fashion; but, if such return signal is not received within a predetermined length of time, the apparatus then causes an automatic application of the train brakes. This form also withholds the return radio signal for stopping the train if a vehicle is stalled on the railroad track at the crossing.

United States Patent [72] Inventor John E. Freeliafer Pittsford, N.Y.[21 Appl. No. 768,633 [22] Filed Oct. 18, I968 [45] Patented Jan. 26,I971 7 3 I Assignee General Signal Corporation Rochester, N.Y.

a corporation of New York [54] SIGNALS AT HIGHWAY CROSSINGS FOR HIGH3,268,723 8/1966 Failoret al IE REGULAR WARNING Primary Examiner-ArthurL. La Point Assistant Examiner-George H. Libman Attorney-Harold S. WynnABSTRACT: The system differentiates between high speed trains andregular trains by having inductive means partly on the car and partly onthe wayside for the high speed trains, While the regular speed trainscooperate with detector track circuit apparatus on the wayside forinitiating the warning signals at the highway crossing. The inductivemeans on the wayside is located considerably in advance of the detectortrack circuit apparatus, but acts through such apparatus for initiatingthe warning signals. The warning signals given at the crossing continuetheir operation until the train has passed the highway. In one form ofthe invention, the car-carried equipment includes a radio transmitterwhich is initiated when the train passes the wayside inductive means.The transmission of such radio signal initiates the warning at thehighway crossing and also causes the transmission of a return radiosignal. If such return radio signal is promptly received, the train cancontinue in the usual fashion; but, if such return signal is notreceived within a predetermined length of time, the apparatus thencauses an automatic application of the train brakes. This form alsowithholds the return radio signal for stopping the train if a vehicle isstalled on the railroad track at the crossing.

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I I I WARNING SIGNAL BARRIERS CONTROL APPARATUS [,l? w l l I i I WARNINGSIGNALS REGULAR SPEED TRAIN- NO INERT INDUCTORS HIGH SPEED TRAIN- ONEINERT INDUCTOR ON RIGHT S|DE ONLY OF LEADING CAR SIGNALS AT HIGHWAYCROSSINGS FOR HIGH SPEED TRAINS BACKGROUND OF THE INVENTION Thisinvention relates to highway-crossing warning systems; but moreparticularly pertains to such a system which distinguishes between highspeed trains and regular speed trains so as to advance the point atwhich the warning is initiated by high speed trains.

Various systems have been proposed for relating the speed of a train tothe response of wayside apparatus to give a warning at the highwaycrossing at a substantially uniform time in advance of the trainarriving at the crossing regardless of the speed of the train. Most ofthese systems are useful for giving a substantially uniform warning timeregardless of the speed of the regular trains; but, when very high speedtrains are used, the distance in advance of the crossing required forthe initial warning becomes much greater than the distance for regularspeed trains. However, the use of track circuits is very expensive whenthey are extended for greater than normal distances for the relativelyfew high speed trains passing over the trackway.

The present invention proposes to provide apparatus where no trackcircuits are employed beyond the detection zone for the regular speedtrains; and yet, the approach of a high speed train actually initiatesthe warning from a point appropriately located in advance of thedetector zone. Also, such apparatus is effective until the trainactually passes the highway in the usual way.

The present invention proposes to provide a means for indicating thepassage of a train which operates in a safe and proven manner. Suchmeans uses magnetic inductors and receivers the same as employed inintermittent inductive train control systems which have been found to bevery reliable over a period of years.

In addition, the present invention provides a way of including theapparatus for the approach indication mainly in traincarried equipmentwhich also includes a check upon the complete communication between thetrain and the wayside equipment. Also, the train carried equipmentincludes means for effecting stoppage of a train both upon failure ofcommunication and also upon the presence of a stalled nonmoving vehicleon the crossing track. The communication in this form of the inventionis via radio channels.

SUMMARY OF THE INVENTION Warning signal means is provided at the highwaycrossing for warning vehicles of an approaching train. The usual trackcircuit apparatus is employed for detecting the presence and approach ofa regular speed train for causing operation of the warning system.However, inductive means is located on the wayside at a distance beyondthe track circuit apparatus for the detecting of only the passage andapproach of a high speed train. Such detection of the high speed trainis effective to act on the regular track circuit apparatus the same asif it were shunted by a regular train to efi'ect the initiation of thewarning signal.

Further, a system is provided having warning signal means at a highwaycrossing for warning vehicles of an approaching train when renderedactive. Means is also provided at a wayside location for identifying thepassage of a vehicle at that point and initiating control means on thetrain for indicating the passage of that point. The control means wheninitiated transmits a signal to the highway crossing for rendering thewarning signal active. However, if the transmitted signal is promptlyreceived, a return transmission means is rendered active to transmit areturn signal to the train. The apparatus on the train acts to apply thebrakes and remove the power from the train if a return signal fails tobe received a predetermined time following the initial reception of thesignal from the wayside identifying the passage of the train.

In addition, there is means at the highway crossing for detecting thepresence of a stalled vehicle on the crossing and thereby preventing thetransmission of the return signal for removing the power and applyingthe brakes in the presence ofa dangerous condition.

For a better understanding of the present invention, together with otherand further objects thereof, reference should be made to the followingdescription, taken in connection with the accompanying drawings, whileits scope will be pointed out in the appended claims.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. I is a diagrammatic illustrationof one organization for effecting the initiation of the warning signalsat the highway crossing in accordance with high speed trains as comparedto low speed trains for both directions of traffic;

FIG. 2 is a diagrammatic illustration of a different organization fordistinguishing the high speed trains from the regular speed trains;

FIG. 3 is a diagrammatic illustration of a wayside apparatus responsiveto a radio control signal from a train passing an identified point forinitiating the crossing signal; and

FIGv 4 diagrammatically illustrates a train carried equipment whichcooperates with the apparatus of FIG. 3 for producing such radio controlsignal upon the passage of the identified point; and also, whichrequires the reception of a return radio signal in order for the trainto proceed.

DESCRIPTION OF PREFERRED EMBODIMENTS The first form of the inventionconstitutes apparatus responsive to traffic in either direction forinitiating the highway crossing for high speed trains before they reachthe track circuit detecting apparatus provided for the regular speedtrains.

The locomotives for the high speed trains each have an inductor on theirright hand side; but, the regular speed trains do not have anyinductors. This means that a regular speed train is detected by thedetector track circuit apparatus for initiating the highway-crossingwarning signals to give the usual approach warning of at least 20seconds before the train reaches the crossing. However, the approach ofa high speed train actuates the wayside receiver on the right side ofthe track, and its control reaches ahead from its advanced position todeenergize the detector track circuit apparatus the same as if the trainwere actually shunting the rails. This condition is maintained until thetrain actually passes over the highway crossing at which time a resetcontrol is established. The leaving inductor location is on the oppositeside of the track so that the train proceeds without further actuating awayside receiver. 7,

It is assumed that such locomotive with its inductor on the right-handside of the locomotive is turned around on a turntable at the end of itsroute, so that its inductor will actuate the receiver on the oppositeside of the track for the opposite direction of travel.

As an alternative, a locomotive may have two inductors, one on eachside. These inductors would have choke windings. These choke windingswould be controlled by an automatic reversing switch which would rendereffective the inductor on the right-hand side of the locomotive for theparticular direction which it is then traveling; and which would renderthe other inductor on the other side ineffective. An inductor isineffective when its choke winding is short circuited; but, when itschoke winding is open circuited, it is then effective to actuate awayside receiver.

The second form of the invention provides for distinguishing' the highspeed trains from the regular speed trains by providing an inductor oneach car of the high speed train. These inductors are located in thecenter of each car so as to pass over each wayside receiver regardlessof its direction. The wayside receivers are located between the tworails of the track to cooperate with the inductors.

Regular speed trains would be detected by the detector track circuitapparatus in the usual way; but each high speed train would act on thewayside receiver to each of the cars of that train. The activation of areceiver would cause its control to reach ahead to act upon the detectortrack circuit the same as if the train were passing over it and shuntingits rails. The repeated response of a receiver for each car of the trainis rendered ineffective to interrupt the initial control established.Also, the initial control established is maintained until the trainreaches the crossing. The operation of the leaving wayside receiver isnot effective on the apparatus. although the warning signals arerestored to their normal ineffective conditions after the rear of thetrain has passed over the highway crossing.

Thus, each high speed train is detected in the same way to give anadvance warning regardless of its direction of travel. This organizationavoids the necessity of a turntable and also avoids the use of anautomatic reversing switch and choke coils on the car-carried inductors,above described in connec tion with the first form.

Third form of the invention proposes that the regular speed trains givewarning signals by the usual detector track circuit apparatus; but thehigh speed trains cause warning signals to be initiated from the trainat an advanced point which is designated by an inductor on the wayside.Such inductor activates a receiver on the locomotive of the train whichin turn transmits a radio signal to the wayside crossing equipment. Ifsuch radio signal is properly received at the highway crossing, a returnradio signal is transmitted. Such return radio signal is received on thelocomotive and forestalls automatic removal of power and application ofthe brakes. In other words, a limited time is given after the locomotiveequipment receives its initial control and transmits its control radiosignal within which the return signal must be received in order to keepthe tram going.

However, the locomotive equipment continues to transmit its radiocontrol signal until a different and longer time runs out. Thisdifferent time is sufficient for the high speed train to actually occupythe detector track circuit. When such time has elapsed, the locomotiveapparatus is reset in readiness for the next highway crossing. in thisway, once the highway warning signals are rendered active they remainactive until the train has passed the crossing.

In addition, suitable detector means is provided adjacent the highwaycrossing to detect the presence of stalled vehicles with such detectioncausing the failure of transmission of the return radio signal. Thiscauses an immediate automatic brake application to the train and powerremoval from the locomotive.

These several forms of the invention have the common feature of reachingahead from an advance location to control the regular warning devices ata highway crossing to stop the highway traffic without employing trackcircuits between such advanced location and the usual detector trackcircuits in approach to the highway crossing. The detailed operation ofthese several fonns will now be given.

F lRST FORM With regard to FIG. 1 of the accompanying drawings, astretch of track with rails 7 is shown having the roadway of a highway 8crossing such rails. The rails 7 are divided into detector sections bysuitable overlay track circuits of the high frequency type using forexample, frequencies in the range 1,000 to 5,000 cycles per secondsuitably modulated by frequencies in the order of 80 to 240 cycles persecond. For example, a section is established by the connection of transmitter 11 for frequency fl across the rails at 9 and extends to thereceiver 15 for frequency fl which is connected across the rails at 10.Another section is established by connecting the transmitter 11 forfrequency f2 across the rails at 18 with a receiver 15 for frequency f2connected across the rails at 19. It is noted that these two detectorsections overlap the highway crossing 8 to provide the effect of anisland track circuit.

These overlay track circuits can be applied to the track railsregardless of whether direct current track circuits. coded trackcircuits. or other high frequency track circuits are otherwise appliedto the rails for regular signaling purposes. These overlaycd trackcircuits do not shunt the rails because the conncctions are made throughcapacitors of sufficient size to carry the transmitted high frequencies;and. in some instances, the receivers are coupled to the rails throughthe use of coupling loops. Such overlay track circuits are well-known inthe art and have been described for example in the Handbook 76 entitledShunt Overlay Track Circuits." published in 1962 by the General SignalCorporation.

The two track circuit sections transmit different frequencies suitablydesignated as /I andf2 so that each circuit acts wholly independently ofthe other.

The transmitters ll are constructed to produce their distinctivemodulated frequency; and the receivers 15 are constructed to respond totheir distinctive modulated frequency and effect the energization oftheir respective track relays but to allow such track relays to releasewhen their associated frequency ceases.

It is noted that the warning signals at the crossing are required to beset into operation at least 20 seconds in advance of the arrival of thefastest train which may pass over the crossing. 1

If the highest speed of the regular trains happens to be 60 mph, thewarning would have to be initiated when the train is 1,760 feet awayfrom the crossing. lf the speeds of the regular trains have a higher orlower maximum the distance of course would be adjusted accordingly.Assuming that the highest speed of the regular trains is 60 mph, thenthe actual warning time is established by providing a track circuit ofsuitable length. For example, the detector circuit from the connection10 to the connection 9 is sufficiently long to include the highway andthus its length would be in the order of 1,800 feet.

The track relays TR] and TR2 are interlocked by suitable apparatusindicated by the dotted rectangle 16. which interlocking in turnprovides for operation of the control apparatus 17. This controlapparatus in turn renders the warning signals WSA active or inactivedependent upon whether or not a train is approaching. The suitablecontrol apparatus 17 also effects operation of the gates or barriers WSBin accordance with the usual control principles for automatic barriers.

One such interlocking and control apparatus is shown in the prior patentto Luft US. Pat. No. 3,035,l67 dated May I5, 1962. This patentillustrates the control of both warning signals and automatic barriersin connection with the overlapping of high frequency track circuits asshown herein. It should also be understood that other forms of trackcircuits may be employed such as the usual direct current trackcircuits. In which case, an island-type track circuit can be usedadjacent the highway 8. On the other hand a high frequency track circuitcan be used as the island circuit such as shown in Crain US. Pat. No.3,025,393 dated Mar. 13, 1962.

Although warning signals and automatic barriers are designatedseparately in the drawings, it is to be understood that the term warningsignals is also intended to be inclusive of automatic barriers sincesuch barriers are of the frangible type and are indicative of thedesired stopped condition of a vehicle rather than forcing an actualstopping of the vehicle.

In addition to the detector track circuit apparatus above described asbeing associated with the highway crossing for giving warning signals toapproaching highway vehicles, suitable apparatus is also provided toinitiate an advance warning for high speed trains. For example, if thehigh speed trains are expected to run at a maximum of mph, the advancewarning distance from the connection 9 to the wayside receiver R1 wouldbe in the order of 1,760 feet.

The wayside receiver R1 of FIG. 1 has a winding 20 on it which isenergized from the battery Bl through the detector relay D1 andrectifier unit 14. The energy in this circuit flows continually andmagnetizcs the laminated iron core structure of receiver R1. Thiscircuitry also energizes the detector relay D1 which supplies stickenergy to the relay Q1 from through circuit including from contact 21 ofrelay D1, front contact 22 of relay ()1, windings of relay O1, to

Let us assume that a high speed train is approaching. It is carrying ahinductor (not shown) on the right-hand side of its lead locomotive. Thisinductor is an appropriate stacking of iron laminations suitably mountedon the train to cooperate with the wayside receivers.

When the inductor approaches the receiver R1, the EMF induced in winding20 tends to slightly aid the battery B]; but as the inductor moves overand away fromthe receiver R1, a substantial EMF is produced in thewinding 20 which first opposes the battery B1 and then aids it beforereturning to normal. The essential point is that the opposing EMFreduces the current in relay D1 below its release value and it quicklydrops away. The presence of the rectifier unit 14 in the circuit forrelay D1 prevents its over energization in the reverse direction shouldthe opposing EMF produced by the winding 20 exceed the voltage of thebattery Bl when the locomotive inductor passes over the receiver veryrapidly at the high speeds.

The momentary deenergization of the relay D1 upon the pamage of theinductor (not shownYcauses the quick release of contact 21 which in turncauses relay Q1 to immediately open from contact 22 and front contact12. Open front contact 22 maintains relay 0] deenergized although frontcontact 21 again closes almost immediately.

The opening of front contact 12 disconnects the transmitter 11 so thatits frequency fl is no longer transmitted. The failure to receivefrequency fl by the receiver 15 at the connection causes the relay TR1to release. This initiates the warning signals at the highway throughthe interlocking and control apparatus 16 and 17. This assures that thewarning signals remain active during the approach of the train.

When the train occupies the track section between the connections 9 and19, the rails 7 are shunted which prevents the transmission of frequencyfl the same as the opening of contact 12 of the relay Q1. The passage ofthe train past the connection 19 causes the receiver for frequency f2 torelease the track relay TR2 and close its back contact 23. Thiscompletes a pickup circuit for relay Q1, which causes front contact 22to reset the relay Q1. The warning signals are maintained because thetrain still shunts the track rails 7 preventing the frequency fl frompicking up the track relay TR1.

When the train passes wholly beyond the highway crossing 8 and theconnection 10, the frequency fl is again received. by the receiver 15 toenergize the track relay TR1. This picking up of relay TR1 causes thesignals at the crossing to be rendered inactive and restored to normalat rest conditions. However, since the track rails 7 are still shunted,the frequency 12' is kept from the receiver 15 for the connection 19 andthe relay TR2 remains deenergized, but this does not affect the warningsignals because of the stored conditions in the interlocking apparatus16. When the train passes wholly out of the detector track section area,past the connection 18, the track relays TR1 and TR2 are both energizedand the interlocking apparatus is fully restored to normal for the nexttrain.

The interlocking apparatus 16 includes directional relay means,mechanically interlocked relays or the like, so as to determine that thetraffic is from left to right to maintain the warning signals operativeonly until the train has wholly past the crossing. Such interlockingapparatus is also effective to prevent the leaving train from affectingthe warning apparatus although the track relay TR2 is released as abovedescribed.

.A similar operation for a train traveling from right to left would takeplace. Such train would initially control the apparatus when the trainpasses receiver R2, but subsequent operating conditions would of coursebe in reverse sequence. This also assumes that the locomotive has beenturned around, or a selection between two car-carried inductors is madeas previously pointed out.

SECOND FORM With reference to FIG. 2, the same detector track circuitapparatus is employed along the rails 7 for the highway crossing 8 asshown in FIG. 1 and described in connection therewith. The interlockingand control apparatus 17-16 is also the same as described in connectionwith FIG. I.

The receivers R1 and R2 of this FIG. are connected to their detectorrelays D1 and D2 respectively, and are operated the same as disclosed inconnection with FIG. 1; but, the receivers R1 and R2 are located betweenthe track rails 7 instead of on opposite sides of the track way as shownin FIG. 1. This is so that the inductors in the middle of the cars of atrain will cooperate with the wayside receivers regardless of thedirection of movement. Also, this form is particularly adaptable torapid transit cars or a multiple unit train where each car of such trainis self-propelled and may be operated alone or in a train of cars. Forthis reason, each car has its own inductor located so as to cooperatewith the receivers located between the rails. Such midposition isparticularly useful where the cars may operate in either directionwithout being turned around on a turntable.

This form of the invention may have repeated detections of the inductorson a high speed train but this does not cause any adverse effects as thetrain passes the wayside receiver in approach to the crossing. Also, asthe train is leaving the crossing, the multiple actuations of thewayside receiver on such leaving side of the crossing are renderedineffective because of the storage of the fact that the train entered atthe other end of the stretch of track.

When the apparatus is being installed, it is assumed that the detectortrack circuit apparatus is installed first, and that the track relaysTR1 and TR2 will be normally energized. It is also assumed that thewayside receivers R1 and R2 with their respective batteries willnormally provide for the energized condition of their detector relays D1and D2. However, the relays Q1, 02, AD, and ADP, may not readily becaused to assume their normal conditions. For this reason, a so-callednor malizing button 25 is providedto be momentarily actuated uponinstallation of the apparatus, and upon any repair work or otherconditions requiring the same. For example, the actuation of thisself-restoring button 25 closes back contact 26 connecting through backcontact 26. front contact 27 of track relay TR2, winding of relay O1, toRelay Q1 then sticks up through front contact 28 of relay D1. Also, theac tuation of button 25 completes a similar pickup circuit for relay Q2from through back contact 26 of button 25, front contact 34 of relayTR1, winding of relay O2 to Relay Q2 then sticks up through frontcontact 36 of relay D2.

Since either the relay Q1 or Q2, or both, may have been initiallydeenergized, or may have become deenergized due to the momentary releaseof either one or the other or both of the relays D1 and D2, the relay ADis picked up by reason of either back contact 30 or back contact 33, orboth. lf this had occurred, then the energized condition of relay ADwould have closed front contact 31 to energize the slow release relayADP through an obvious circuit. Since this relay ADP is constructed tobe slow released, it is also slightly slow to pick up. Since both relayQ1 and Q2 are picked up by the actuation of button 25, the relay ADwould be held stuck up through its stick circuit; but the actuation ofthe button 25 also opens contact 40 which opens such stick circuit sothat relay AD is released. This in turn deenergizes the relay ADP. Uponthe release of button 25 all of the relays in FIG. 2 can be in thenormal positions illustrated.

Since both of the detector relays D1 and D2 are picked up, a circuit isclosed for charging the capacitor C from through front contact 43 ofrelay D1, front contact 44 of relay D2, capacitor C, to

Let us now assume that a train is proceeding from the west or left-handend of the stretch of track and its inductor passes over the receiverR1. This will cause a momentary deenergization of the relay D], asprevioiisly described. which is sufficient to allow the relay Ql to openits contacts and decnergize its stick circuit. The closure of backcontact 30 of relay 01 will cause relay AD to pick up which in turncloses contact 31 and energizes relay ADP to cause it to close its frontcontacts in due course. As a consequence of the momentary release ofrelay D1, back contact 38 of relay D] is momentarily closed and brieflyconnects charged capacitor C across relay ADP. Since relay ADP isslightly slow to pick up, this charge does not actually cause itsoperation to a picked up condition, but very shortly its picked upcondition is actually accomplished by its energization through frontcontact 31 as previously described. This picked-up condition of relayADP is maintained until the train proceeds further over the track aslater described.

However, in the meantime this high speed train may have several cars andthe inductor on each of them will each cause the detector relay D1 to bemomentarily released; but, no action takes place with regard to the restof the apparatus because the relay has no way of picking up betweenrepeated operations of the relay Dl. Thus, the relay 01 remainsdeenergized and opens front contact 12 causing the stopping of thetransmission of the frequency fl over the detector track circuitapparatus the same as if the rails 7 were shunted. This causes therelease of the track relay TRl. Such release of the relay TRl initiatesthe interlocking and control apparatus to cause the warning signals atthe highway crossing to become active immediately following theactivation of receiver R1.

As the train proceeds from the receiver R1 toward the east, the steadydeenergization of relay Q1 maintains the warning signals and the rest ofthe apparatus in condition for the entry of the train into the detectortrack circuit apparatus. When the train passes the connection 9, itswheels shunt the rails and thus makes it no longer necessary to maintainthe relay Q1 deenergized although it actually does stay in thatcondition.

When the train passes the connection 19, its wheels shunt the trackrails 7 and prevents the frequency ]2 from being received by theassociated receiver 15 for maintaining the track relay TR2 energized.Thus, the track relay TR2 is released. Since the relay ADP is picked upclosing front contact 46, the closing of back contact 27 of relay TR2completes a pickup circuit for the relay 01 through an obvious circuit.The closure of front contact 29 sticks relay Q1. But the opening of itsback contact 30 does not release the relay AD because of its stickcircuit previously pointed out is now closed. This maintains relay ADPsteadily energized through front contact 31 so that it remains pickedup.

Incidentally, under these conditions a circuit is closed for chargingthe capacitor C from through front contact 43 of relay D1, front contact44 of relay D2, capacitor C, to This circuit is closed when relay ADPinitially picks up, but it is steadily closed when relay D1 is steadilypicked up following the passage of the last car of the train past thereceiver R1. When relay ADP is picked up, it causes front contact 48 tomaintain relay Q2 picked up as later described.

When the train entirely passes the connection 10, the frequency fl isreceived by the receiver 15 associated therewith and causes the trackrelay TRl to pick up. This removes the warning signals from the crossingbecause the interlocking apparatus prevents the deenergized condition ofTR2 from being effective since it was deenergized later than thedeenergization of relay TRl. The train then proceeds through the trackcircuit toward the connection 18.

When the train entirely passes this connection 18, the frequency f2 canthen flow through the rails to be received by the receiver 15 at theconnection 19 and energizes the track relay TR2. In brief, when thetrain entirely leaves the detector track circuit apparatus both relaysTR2 and TR! are picked up; but, under these circumstances, the relay ADis picked up maintaining the relay ADP picked up. Also, capacitor C isfully charged.

When the first car of the train with an inductor passes over thereceiver R2, the relay D2 is momentarily released but the opening offront contadt 36 cannot release 02 because of the closed front contact48 of relay ADP. However. the opening of front contact 39 of relay D2causes the relay AD to release because of its open stick circuit.Although contact 3| opens promptly, the relay ADP remains picked upbecause the capacitor C is discharged through it by the back contact 49of relay D2. In other words, a momentary release of the relay D2 causesthe relay ADP to remain picked up.

Assuming that asecond car of the train also has an inductor which passesover the receiver R2, the relay D2 would again be momentarily released.Since the preceding picked-up condition of D2 closed front contact 44,the capacitor C would be recharged, so that the momentary closure ofback contact 49 would again cause capacitor C to discharge through ADP.In brief, the capacitor C is charged during the periods that relay D2 ispicked up and is discharged through the relay ADP during the periodsthat D2 is dropped away. The relay ADP remains picked up between itssuccessive encrgizations due to its slow release characteristics.However, when the high speed train has wholly passed the receiver R2,the relay D2 remains picked up which causes front contact 36 to maintainthe relay Q2 picked up although the relay ADP releases because ofopen-back contact 49. The relay ADP would release in any event althoughthe back contact 49 did not open because the capacitor C would shortlybecome discharged. The relay ADP would release after an interval of timeaccording to its slow release characteristics.

In connection with the regular speed train, which has no inductors, itis detected only by the detector track circuit apparatus as previouslydescribed. The operation of the high speed trains in the oppositedirection is of course analogous to the description already given but inthe reverse sequence. It is understood that the interlocking and controlapparatus responds to the sequence of operations to appropriatelycontrol the highway warning signals.

THIRD FORM (FIGS. 3 AND 4) With reference to FIG. 3, a stretch of trackhaving rails 7 is shown intersecting the highway crossing 8 the same asin prior FIGS. 1 and 2. However, the detector track circuit apparatushere shown relates only to the control of the warning signals at thecrossing for railroad traffic in a single direction. Suitable trackcircuit detection is provided in approach to the highway crossing in theform of what is known as an overlay track circuit with transmitter llconnected across the rails at 9 and with a receiver 15 connected acrossthe rails at 10. This overlay track circuit is the same as described inconnection with FIG. 1. Therefore, the connection 9 is spaced from theconnection 10 to provide the usual length track circuit for a standardwarning time of 20 seconds for trains of usual speed such as 60 mph. Theconnection 9 at the left is therefore approximately 1,800 feet from theconnection 10 to the right of the crossing assuming that the 1,760 feetis reached for the regular warning distance at the left of the crossing,and that the roadway is approximately 40 feet wide.

The transmitter 11 transmits a modulated frequency fl through theconnection 9 over the track rails 7 to the connection 10 and throughreceiver 15 for energizing the track relay TR. The circuitry from thereceiver 15 for energizing the track relay TR includes back contact 50of the relay RRS which is controlled by the radio receiver 51 inresponse to the radio frequency f5 from the approaching high speedtrain. When a radio signal is received from the high speed train, fromcontact 53 of relay RRS is picked up which closes a circuit for theradio transmitter 52 including front contact 54 of relay SVR.

Also, associated with the highway crossing 8 is a presence sonicdetector PD which provides for the energization of the relay PDRwhenever a vehicle is on the crossing within its range of detection.Another sonic detector MD preferably of the motion-detecting type, suchas the detector which operates on the Doppler principle, is located todetect any movement by vehicles which are passing over the crossing andin turn are also detected by the presence detector PD. When vehiclemovement is detected by the motion detector MD, it then energizes therelay MDR. Both of these detectors are required because the usualmovements of traffic would be detected by the presence detector PD andat least cause the relay PDR to be intermittently picked up andreleased. In a similar way, the moving traffic would be detected by themotion detector MD and cause intermittent operation of relay MDR. Sincethe purpose of this organization is to detect a stalled vehicle, thedetection of a vehicle that is not moving results in the deenergizationof the relay MDR and the energization of therelay PDR. This effects thedropping away of the relay SVR which prevents the transmission of areturn radio signal in response to the receipt of a control radio signalby the radio receiver 51.

Under normal conditions, the vehicles are in motion so that motion andpresence are detected substantially simultaneously. This closes thefront contact 56 of relay MDR and maintains SVR energized while therelay PDR is picked up opening back contact 55. The detection of anormal vehicle passing over the crossing cannot release the relay SVR.Thus, the return radio signal of frequency f6 is transmitted by radiotransmitter 52 and the train continues to operate in the usual way.

The wayside inductor 60 is of the inert type formed of laminatedmagnetic material such as iron, and it is located at an appropriatedistance from the regular detector track circuit apparatus so as toprovide the appropriate warning distance for the additional speed atwhich the high speed trains run. For example, if the regular speedtrains run at 60 mph. and such speed is doubled to 120 mph, then thewarning distance from the crossing would be in the order of 3,520 feet.Since the detector track circuit apparatus provides a warning distanceof 1,760 feet then the inductor will be a further I ,760 feet from thefirstconnection 9 to provide the advance warning distance as illustratedin FIG. 3.

TRAIN-CARRIED EQUIPMENT OF FIG. 4

Each high speed train has train carried equipment which will respond tothe wayside inductor at the appropriate advance warning distance;whereas, each regular speed train has no train-carried receiver andassociated equipment. A regular speed train is not detected until itreaches the detector track circuit apparatus of FIG. 3.

The train-carried equipment for each high speed train includes two radiotransmitters 61 and 63 and also includes two radio receivers 62 and 64.The radio transmitter 61 and the radio receiver 62 are rendered activewhen the contacts 70, 71, 72,'and 73 are in their left-hand positions;but the radio transmitter 63 and the radio receiver 64 are renderedactive when the contacts 70, 71, 72, and 73 are in their righthandpositions. These two sets of receivers and transmitters are provided asalternates so that upon the failure of one set, the other set can beimmediately switched into activity. The contacts 70, 71, 72, and 73 aremanually actuated simultaneously by suitable means.

The train-carried equipment also includes a receiver 66 constructed ofiron laminations in the usual way. This receiver 66 is located on thelocomotive in a manner to cooperate with the wayside inductor 60 of FIG.3. This receiver 66 is connected to a suitable direct current source toenergize the primary winding P directly, and to energizethe secondarywinding S and relay R1 in series. During the installation of the system,power will be applied (as indicated) through suitable terminals and amaster control switch (not shown). The application of this power willcause energy to be supplied to effect the pickup of relay TEP, shortlyto be described, which will then discharge the capacitor 83 throughfront contact 84 and cause the relay B to be picked up. Relay B is thenstuck up through front contacts 85 and 86. More specifically, whenenergy is first placed on the heel of contact 80, the back contact 80energizes the thermal relay TE through back contact 81 of relay TEP.After a suitable time measured by the terminal relay TE, the contact 82closes and energizes the relay TEP through an obvious circuit. When thecontacts of relay TEP pick up, front contact 81 connects the thermalwinding through the relay TEP which reduces the current in such thermalrelay to a value where its contact 82 restores to a normal condition.When the relay TEP is deenergized as shown. the capacitor 83 isenergized through back contact 84 of relay TEP. Thus, when the relay TEPpicks up, the capacitor 83 is discharged through the lower winding ofrelay B which causes its contacts to be picked up. The closure of frontcontact 85 with the closed condition of front contact 86 causes therelay B to be energized through a stick circuit which will be readilyapparent. The opening of back contact 80 of relay B removes the energyfrom relay TEP so that it releases and again closes back contact 84 tosupply energy to the capacitor 83.

Before the train can proceed, the train brakes must be removed. With thetrain standing still, the governor contacts 90 are closed so that theactuation of the manual reset button closes contacts 91 to supply energyto the relay BR. Such relay BR picks up and closes front contact 92 tocomplete stick circuit through contact of relay B. The closure of frontcontact 93 of relay BR immediately completes an obvious circuit forpicking up relay BRP. The operation of contact 94 is in a releasedcondition and causes the brakes to be removed when the contact is in apicked-up position.

OPERATION OF FIG. 3 AND 4 Let us assume that the train carried equipmenton a locomotive as shown in FIG. 4 has its receiver 66 located so thatit passes directly over the inductor 60. This movement of the receiver66 over the inductor 60 induces a current in the secondary winding ofthe receiver 66 which is in opposition to the current normally flowingin that circuit so as to reduce the current therein below a holdingvalue for the relay R1. The release of relay R1 in turn is repeated bythe relay B because of open contact 86 in its stick circuit. The releaseof relay B is repeated into the relay BR because of open contact 80.Relay BR opens contact 93 and initiates a relatively short timing periodduring which a return radio signal can be received to forestall theapplication of the brakes and removal of passer. Also, the closure ofback contact 80 starts a timing operation of larger duration as willshortly be described.

The closure of back contact 96 of relay B renders the radio transmitter61 active for sending a radio control signal of frequency f5 to theradio receiver 51 of FIG. 3. This receiver 51 then immediately actuatesthe relay RRS to open back contact 50 and release the normally energizedtrack relay TR. Thus, contact 59 causes the warning signal apparatus atthe crossing to be set into operation. The closure of front contact 53(assuming no vehicle is stalled on the crossing) closes a circuitthrough front contact 53 and front contact 54 to activate the radiotransmitter 52 to transmit a return signal of frequency f6 to the radioreceiver 62 of FIG. 4. This signal acts through contact 73 to energizethe relay RRT which picks up contact 97 and completes a holding circuitthrough contact 98 of relay BRP to energize the relay BR. So long as thecontrol radio signal is transmitted, the return radio signal will bereceived and the relay BR and its repeater relay BRP will be maintainedenergized. The continued receipt of the radio control signal by radioreceiver 51 continues the warning signal apparatus in operation advisingvehicles that a high speed train is approaching.

When the train reaches the detector track circuit apparatus, it shuntsthe rails 7 which causes the continued operation of the warning signalsirrespective of the continued receipt of the radio control signal. Thus,the thermal time element relay TE is provided with a time of operationsufficient for the train to travel at its high speed from the inductor60 to and past the first track connection 9 (from the left) as shown inFIG. 3. When the thermal relay TE has operated after its predeterminedtime has elapsed, it picks up the relay TEP and discharges the capacitor837W the relay B. This picks up the relay B so that it sticks up throughfront contact 86 of relay R1.

The opening of back contact 96 deencrgizes the radio transmitter 61causing the radio control signal of frequency/ to cease. This thenreleases the relay RRS at the wayside apparatus of FIG. 3 causing thereturn radio signal of frequencyf 6 to cease. The resulting release ofthe contact 97 of relay RRT is ineffective to release the relay BRbecause the relay BR has its stick circuit closed through front contact80. The continued closure of contact 93 of relay BR causes the relay BRPto be maintained energized which in turn prevents any operation of thetrain brakes. The train thus continues through the track circuit andpast the second connection 10. When the train has fully passed thecrossing and the connection 10, the frequency fl will be received by thereceiver l5 and result in the energization of the track relay TR forremoving the warning signals from the highway.

On the other hand, if when the train passed the inductor 60, a stalledvehicle was located on the highway crossing, the return radio signalwould not be transmitted because of the open condition of contact 54 ofrelay SVR. This would then allow the relay BR to remain deenergizedsufficiently long for the relay BRP to release and apply the brakes andremove the power from the train. Any subsequent transmission of thereturn radio signal for any reason what so ever such as the removal ofthe stalled vehicle, would not reenergize the relay BR because the relayBRP is released. In other words, the train must stop. After the trainhas stopped as indicated by its contacts 90 of the governor, thetrainman can reset the apparatus by picking up the relay BR. Assumingthat the time of thermal relay TE has elapsed and that relay TEP haspicked up and had in turn picked up the relay B, then the relay BR wouldbe stuck up through front contact A.

it is desired to point out that the time of release of relay BRP is justslightly longer than the time required to effect the rapid return of theradio signal. if such signal is not returned immediately, the brakes ofthe train are therefore applied.

In connection with the operation of the thermal relay TE its time can bedelayed if desired almost until the train reaches the highway crossingso that the removal of the return radio signal could during such timeapply the brakes to the train. But this is thought to be unnecessary,since the critical time for detecting the stalled vehicle is immediatelyfollowing the initiation of the highway-warning signals and the loweringof the gate barriers. After such barriers have been lowered, no furthervehicles are supposed to enter the crossing area and any vehicle thatwas in the crossing area before the gate was lowered should then shortlyremove itself from the crossing area. Thus, the time element measured bythe thermal relay TE is essentially the time required for the high speedtrain to reach the track circuit apparatus and be detected by it.

Should the train have its brakes applied because of failure in thetrain-carried radio transmitting and receiving equipment, the operatorcan manually actuate the contacts 70, 71, 72, and 73 and determinewhether or not such shift to the auxiliary radio equipment is effectiveto remove the difficulty. Following this he may actuate the manual resetbutton and restore the train-carried equipment to normal in the eventthe substitute of the auxiliary radio equipment is effective.

While there have been described what are at present considered to be thepreferred embodiments of the invention, it will be obvious to thoseskilled in the art that various changes and modifications may be madetherein, without departing from the invention, and its, therefore, aimedin the appending claims to cover all such changes and modifications asfall within the direct spirit and scope of the invention.

Iclaim:

l. A railroad highway-crossing protection system for activating a signalmeans at the crossing for warning vehicles of an approaching train,approach apparatus including track circuit means for detecting thepresence of a train in approach of said crossing and causing theoperation of said signal means at said crossing wherein the improvementcomprises: coupling means including; inductive means on the wayside.located at a distance beyond each end of the track circuit and only oncertain trains, said wayside inductive means responsive to the traincarried inductive means for detecting the passage of only those certaintrains regardless of speed, and means responsive to said coupling meansfor acting upon said track circuit means the same as if any train werepresent to affect the operation of said signal means.

2. A system as specified in claim 1 wherein said means responsive tosaid coupling means remains responsive thereto until reset for actingupon said track circuit and reset means responsive to the rear end ofthe train passing said crossing for resetting said means.

3. A protective system for vehicles at a grade crossing between arailroad track and a highway, a warning signal means at the crossing forwarning vehicles of an approaching train, a track circuit means fordetecting the presence of a train in approach of said crossing andcausing the operation of said warning signal means at said crossing,wherein the improvement comprises: inductive approach means located at asubstantial distance beyond the range of said track circuit fordetecting the approach of certain trains, inductive actuating meanscarried only on the certain trains and operative for actuating saidapproach means, and electrical means responsive to said approach meansin response to the passage of a train carrying said operative actuatingmeans for acting upon said track circuit the same as if any train werepresent on it, whereby the warning signal means at the crossing isinitiated by said certain trains and by those trains not equipped withsaid inductive actuating means at two different distances in approach tothe crossing.

4. A protective system as specified in claim 3 wherein said trackcircuit means is of the overlay relatively high frequency type.

5. A protective system as specified in claim 3 wherein said approachmeans is an inductive receiver distinctively responsive to a high speedtrain.

6. A protective system for vehicles at a grade crossing between arailroad track and a highway comprising, a warning signal means at thecrossing for warning vehicles of an approaching train, a waysideinductor located at a suitable approach distance from the crossing,means on the train responsive to the passage of the train past saidinductor, radio-transmitting means on the train initiated by said meansresponsive to the passage of a wayside inductor and acting to transmit aradio signal, means at the wayside responsive to said radio signal forinitiating operation of said warning signal means, wayside locatedradio-transmitting means associated with said warning signal means whenit is initiated to transmit a return radio signal to said train-carriedapparatus, and means on the train for stopping the movement of saidtrain if said return signal is delayed longer than a predetermined time.

7. A protective system for vehicles at a grade crossing between arailroad track and a highway comprising, a warning signal means at thecrossing for warning vehicles of an approaching train when renderedactive, at wayside location identifier located at a suitable approachdistance from the grade crossing, control means on a train includingmeans responsive to said location identifier for indicating the passageof the train past said location identifier and, means for transmitting aradio signal to said grade crossing for rendering said warning signalmeans active, return transmission means rendered active by the receptionof said radio signal at said highway crossing to transmit a return radiosignal to said train, and means on the train for applying its brakes ifa return radio signal fails to be received a predetermined timefollowing the receipt of the initial signal from the wayside locationidentifi- 8. A system as defined in claim 7 wherein said control meanson the train is restored to normal a predetermined time following thereception of a control from said wayside-identifying means.

9. A system as specified'iritli'preceding claim 8 wherein saidrestoration of said control means after said predetermined time causesthe warning signal means to be rendered inactive unless said train hasapproached to within a predetermined distance of said grade crossingwithin said predetermined time.

10. A system as specified in claim 8 wherein there is approach trackcircuit means adjacent said grade crossing and a predetermined distancein advance of the crossing for detecting the presence of a train andrendering said warning signal means active, whereby said warning signalmeans is continuously rendered active from the time of a train passingsaid wayside location identifier until it passes said grade crossing ifsaid train'occupies said approach track circuit means before saidcontrol means is restored.

11. A system as defined in claim 7 wherein there is means at thecrossing for detecting the presence of a stalled vehicle. said meansbeing effective to prevent the operation of said return transmissionmeans to transmit a return radio signal to the train when a vehicle isstalled on the tracks, whereby said train is automatically caused toimmediately apply the brakes and remove power upon the presence of adangerous condition.

12. A railroad highway missin protection system for activating warningsignal means at the crossing for warning vehicles of an approachingtrain, comprising: approach apparatus means at a preselected distance oneach side of the crossing for at least momentarily detecting thepresence of a train as it passes. control means responsive to saidapproach apparatus means for initiating the operation of the warningsignal means when said train engages said approach apparatus means in adirection approaching the crossing. means at the crossing responsive tothe last car for restoring said control means when the train passes thecrossing, and storage means for registering the passage of said train bysaid approach apparatus. including a capacitor repeatedly charged by therepeated 'operation of the approach means by the train leaving thecrossing to thereby maintain the control means in a restored condition.5 1

13. A system as defined in claim [2 wherein said storage means includesa capacitor repeatedly charged by the repeated operation of saidapproach means by said leaving train to thereby maintain said controlmeans in its restored condition.

1. A railroad highwAy-crossing protection system for activating a signalmeans at the crossing for warning vehicles of an approaching train,approach apparatus including track circuit means for detecting thepresence of a train in approach of said crossing and causing theoperation of said signal means at said crossing wherein the improvementcomprises: coupling means including; inductive means on the wayside,located at a distance beyond each end of the track circuit and only oncertain trains, said wayside inductive means responsive to the traincarried inductive means for detecting the passage of only those certaintrains regardless of speed, and means responsive to said coupling meansfor acting upon said track circuit means the same as if any train werepresent to affect the operation of said signal means.
 2. A system asspecified in claim 1 wherein said means responsive to said couplingmeans remains responsive thereto until reset for acting upon said trackcircuit and reset means responsive to the rear end of the train passingsaid crossing for resetting said means.
 3. A protective system forvehicles at a grade crossing between a railroad track and a highway, awarning signal means at the crossing for warning vehicles of anapproaching train, a track circuit means for detecting the presence of atrain in approach of said crossing and causing the operation of saidwarning signal means at said crossing, wherein the improvementcomprises: inductive approach means located at a substantial distancebeyond the range of said track circuit for detecting the approach ofcertain trains, inductive actuating means carried only on the certaintrains and operative for actuating said approach means, and electricalmeans responsive to said approach means in response to the passage of atrain carrying said operative actuating means for acting upon said trackcircuit the same as if any train were present on it, whereby the warningsignal means at the crossing is initiated by said certain trains and bythose trains not equipped with said inductive actuating means at twodifferent distances in approach to the crossing.
 4. A protective systemas specified in claim 3 wherein said track circuit means is of theoverlay relatively high frequency type.
 5. A protective system asspecified in claim 3 wherein said approach means is an inductivereceiver distinctively responsive to a high speed train.
 6. A protectivesystem for vehicles at a grade crossing between a railroad track and ahighway comprising, a warning signal means at the crossing for warningvehicles of an approaching train, a wayside inductor located at asuitable approach distance from the crossing, means on the trainresponsive to the passage of the train past said inductor,radio-transmitting means on the train initiated by said means responsiveto the passage of a wayside inductor and acting to transmit a radiosignal, means at the wayside responsive to said radio signal forinitiating operation of said warning signal means, wayside locatedradio-transmitting means associated with said warning signal means whenit is initiated to transmit a return radio signal to said train-carriedapparatus, and means on the train for stopping the movement of saidtrain if said return signal is delayed longer than a predetermined time.7. A protective system for vehicles at a grade crossing between arailroad track and a highway comprising, a warning signal means at thecrossing for warning vehicles of an approaching train when renderedactive, a wayside location identifier located at a suitable approachdistance from the grade crossing, control means on a train includingmeans responsive to said location identifier for indicating the passageof the train past said location identifier and, means for transmitting aradio signal to said grade crossing for rendering said warning signalmeans active, return transmission means rendered active by the receptionof said radio signal at said highway crossing to transmit a return radiosignal to said tRain, and means on the train for applying its brakes ifa return radio signal fails to be received a predetermined timefollowing the receipt of the initial signal from the wayside locationidentifier.
 8. A system as defined in claim 7 wherein said control meanson the train is restored to normal a predetermined time following thereception of a control from said wayside-identifying means.
 9. A systemas specified in the preceding claim 8 wherein said restoration of saidcontrol means after said predetermined time causes the warning signalmeans to be rendered inactive unless said train has approached to withina predetermined distance of said grade crossing within saidpredetermined time.
 10. A system as specified in claim 8 wherein thereis approach track circuit means adjacent said grade crossing and apredetermined distance in advance of the crossing for detecting thepresence of a train and rendering said warning signal means active,whereby said warning signal means is continuously rendered active fromthe time of a train passing said wayside location identifier until itpasses said grade crossing if said train occupies said approach trackcircuit means before said control means is restored.
 11. A system asdefined in claim 7 wherein there is means at the crossing for detectingthe presence of a stalled vehicle, said means being effective to preventthe operation of said return transmission means to transmit a returnradio signal to the train when a vehicle is stalled on the tracks,whereby said train is automatically caused to immediately apply thebrakes and remove power upon the presence of a dangerous condition. 12.A railroad highway crossing protection system for activating warningsignal means at the crossing for warning vehicles of an approachingtrain, comprising: approach apparatus means at a preselected distance oneach side of the crossing for at least momentarily detecting thepresence of a train as it passes, control means responsive to saidapproach apparatus means for initiating the operation of the warningsignal means when said train engages said approach apparatus means in adirection approaching the crossing, means at the crossing responsive tothe last car for restoring said control means when the train passes thecrossing, and storage means for registering the passage of said train bysaid approach apparatus, including a capacitor repeatedly charged by therepeated operation of the approach means by the train leaving thecrossing to thereby maintain the control means in a restored condition.13. A system as defined in claim 12 wherein said storage means includesa capacitor repeatedly charged by the repeated operation of saidapproach means by said leaving train to thereby maintain said controlmeans in its restored condition.